Recent years, many medical images showing the interiors of living bodies have been used in medical diagnoses, and, in order to acquire such medical images, various technologies and apparatuses (modalities) such as an X-ray imaging apparatus, X-ray CT (computed tomography) apparatus, ultrasonic (US) diagnosing apparatus, MRI (magnetic resonance imaging) apparatus, and PET (positron emission tomography) apparatus are widely used. Many of the apparatuses are digitalized, and diagnostic information processing systems within hospitals and so on are being constructed. Further, among the imaging technologies, CT and MRI have achieved significant results in detection and evaluation of lesion parts in living bodies because they can acquire and display axial images of a living body at relatively short intervals. Here, an axial image refers to a tomographic image that shows a surface perpendicular or substantially perpendicular to the body axis of an object to be inspected (so-called cross sectional surface). Hereinafter, the axial image is also simply referred to as “slice image”.
When a medical diagnosis is made based on the medical images, in order to observe the change of an affected part over time, slice images obtained by imaging the same part of the same patient at different times may be compared and interpreted. In this case, an image interpretation doctor should search for, with respect to one slice image of interest among one series of images, another slice image showing anatomically the same tomographic image as the one slice image from among another series of images. However, one series of images generated by one imaging include several hundreds or more images, and therefore, the operation requires great effort for the image interpretation doctor.
As a related technology, Japanese Patent Application Publication JP-A-8-294485 discloses an image display system for displaying on an output device plural sets of three-dimensional images including plural tomographic images acquired in plural times of inspection using at least one medical image imaging modality. The image display system includes designating means for designating at least one first pair of tomographic images at substantially identical anatomical tomographic positions from the plural sets of three-dimensional images, tomographic image pair setting means for setting at least one pair of tomographic images at substantially identical anatomical tomographic positions from the plural sets of three-dimensional images based on a tomographic interval of at least one three-dimensional image of the plural sets of three-dimensional images and position information between the first pair of tomographic images, and display control means for allowing the output device to display the set at least one pair of tomographic images.
Further, Japanese Patent Application Publication JP-P2005-124895A discloses an image diagnosing support apparatus for loading plural tomographic images of a chest image of the day (current image) and a chest image in the past (past image) of the same examinee obtained with a medical image imaging apparatus and displaying both images on image display means at the same time. The image diagnosing support apparatus includes extracting means for extracting tracheas and bronchial tubes from the current image and the past image, bronchial bifurcation determining means for respectively determining bronchial bifurcations first bifurcating from the tracheas extracted by the extracting means, and image aligning means for allowing the image display means to display the current image and the past image at the same position in the body axis direction with reference to the current images and the past images corresponding to the bronchial bifurcations respectively determined by the bronchial bifurcation determining means.
As described above, the technique of aligning plural sets of slice images representing anatomically the same sections between two series of images has been known. However, if the alignment is desired for three or more series of images, transformation processing of coordinate systems (alignment processing) between two series of images should be performed with respect to all combinations. For example, in the case where five series of images A-E are aligned with one another, the total twenty times of arithmetic processing between A and B, A and C, . . . , D and E are necessary. Thus, the operation is inefficient, taking a lot of time and effort.